1. Field of the Invention
The present invention relates to a method of collecting a specimen and a method of diagnosing a subject to detect upper digestive system disease. In particular, the present invention relates to a method of collecting a specimen and a method of diagnosing a subject suitable for detection of early cancers, such as pancreatic cancer, biliary tract cancer, and liver cancer.
2. Description of the Related Art
Rapid advancements are being made in methods of examination for upper digestive system diseases (for example, pancreatic cancer, biliary tract cancer, gallstones, stomach cancer, cholecystitis, pancreatitis, liver cancer, and cirrhosis). The prognosis is extremely poor particularly for pancreatic cancer and biliary tract cancer among the upper digestive system diseases. A method of examination is required to enable detection of early stages of these cancers.
Conventionally, research has been reported regarding an early method of examination for cancers in which pancreatic juice and bile are used as specimens. In the method of examination, cytological diagnosis and protein analysis are performed on these specimens. However, in the case of collecting the pancreatic juice or the bile, it is required to insert a catheter into the pancreatic duct or the bile duct. Doctors are required to acquire significant skill in catheter insertion. In addition, catheter insertion may cause pancreatitis as an accidental symptom. Therefore, not all doctors can easily perform the method of examination using pancreatic juice and bile.
A method of pancreatic juice collection is reported in which a catheter is not inserted into the pancreatic duct or the bile duct. Rather, duodenal juice is collected from the duodenum. The duodenal juice contains pancreatic juice and bile discharged from the pancreas and the gall bladder into the duodenum. The duodenal juice is then examined.
For example, “Clinical Gastroenterology and Hepatology 2006; 4(6) pp. 782-789” reports a method of detecting pancreatic cancer in which the interleukin-8 (IL-8) protein concentration present in duodenal juice containing pancreatic juice is measured using the enzyme-linked immunosorbent assay (ELISA) method. In this method, an upper gastrointestinal endoscope is inserted into the patient after fasting. A stimulant of pancreatic juice secretion (secretin) is then administered. Subsequently, pancreatic juice secreted from the duodenal papilla is collected from the duodenum. The pancreatic juice is collected for ten minutes using a catheter that has been threaded through the endoscope. Then, the duodenal juice is frozen for preservation. In addition, the report indicates that a protease inhibitor is added to the collected duodenal juice. It is reported that, as a result, pancreatic cancer can be detected with high sensitivity.
U.S. Pat. No. 5,651,769 reports a method of diagnosing chronic pancreatitis in which duodenal juice is collected from the duodenum using an endoscope. In this method, to prevent gastric juice from mixing with the duodenal juice, a double-lumen catheter is used to collect the duodenal juice. The double-lumen catheter is capable of collecting the gastric juice and the duodenal juice separately. In a manner similar to a secretin test conducted in the conventional method, the patient is administered secretin. Subsequently, the duodenal juice is collected for 15 minutes at a time over a one-hour period.
However, in these methods, the patient is administered a stimulant of pancreatic juice secretion (such as secretin). Therefore, the methods are invasive to patients. In addition, the cost of examination is high due to the cost of the required drugs.
In addition, the collection time for duodenal juice is very long (10 minutes or 15 minutes at a time over a one-hour period). Because a large amount of time is required for examination, the burden placed on patients and doctors is also great.
Furthermore, no reports have been made regarding the timing at which the protease inhibitor is added to the duodenal juice. Therefore, if the protease inhibitor is added to the duodenal juice after the duodenal juice has been collected for 10 minutes or 15 minutes at a time over a one-hour period, the proteins and cells to be measured are broken down by the protease activated in the duodenal juice while the duodenal juice is being collected and accumulated. Therefore, detection accuracy of proteins and cells may decrease.